Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 03, 2012 10:32 am

With additional delays following additional delays I had to wonder if maybe it was a bad idea to combine the COTS 2/3 flights because they could have been further along if they had followed their old plans. I guess combining both flights was done to save time and money but with about a year of cumulative delays I wonder if they have gained anything from it?

What's your opinion?

I made a simple Yes/No kind of poll, but please also post your reasons for picking your answer.

I think it was a bad idea.The final rendezvous might not be that much more difficult than the COTS 2 objectives, but going this close to the station creates additional risks for the station and my guess is that this is the main reasons for all the additional software testing to really make sure everything works as intended.

Doing a COTS 2 mission alone they might have been less concerned and went ahead with the mission with less testing (because there isn't such a risk to the station and the requirements for precision maneuvering are significantly lower).

Then they would have had (in my opinion):-) a launch in 2010 which I think would be a very desirable thing from the PR value of it alone.-) Dragon trunk and solar arrays tested in space by now-) a large part of the Dragon software system verified by now, which would reduce the amount of testing needed before COTS 3 can be done.-) possibly SAVED money? Has anybody an estimate on SpaceX operational costs for a year? Might it actually the case that an additional launch would have been cheaper (assuming that doing COTS 2/3 separately would have accelerated the process and COTS would be over by now for SpaceX)?

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 03, 2012 11:03 am

Good idea.

I think a F9 launch costs $60M (end user price?)? So there is an immediate saving in launch costs. Plus the cost of the capsule itself? $20M? No idea and cannot find the figures.As for the delays - well, they would have had those delays whether they had gone for one or two flights. I don't think PR comes in to it - they won't get $80< worth of PR! Also don't think doing them separately would have been quicker. Probably slower, for a start, they need to make two rockets, two dragons etc which takes at least three months, and wait for launch permissions.

Yes there is a risk with doing both, worth taking I think to save a lot of money, and perhaps time as well.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 03, 2012 12:13 pm

A Falcon 9 Launch costs $54M according to their published prices, but I have no idea what their margins are. The cost of a Dragon is not relevant. If their claims are accurate, they can easily fly the same dragon on both mission.

They won't gain millions of dollars of PR value from a launch, but to many (especially people in congress and the senate) they are still the new kid on the block that can't be trusted yet. Any additional (successful) launch is therefore very important for them to gain traction. They might have an impressive launch manifest, but so far they have (successfully) launched a single commercial payload (RazakSAT on Falcon 1)!

Production times don't play a role either (considering the huge amount of delays) since various pictures in the last year have shown multiple F9s and Dragons (partially) assembled in their factory in Hawthorne. To fulfill their manifest they will have to build and launch ~10 F9s per year very soon, so going from 1 to 2 per year should not be that much of a problem. The COTS 2 F9 has been at the cape since July 2011, the Dragon since October 2011.

What kind of delays are you expecting for a COTS 2 only type mission? Elon Musk has stated in the last press conference, that the delays are more or less only because of additional software testing. My argument is, that a COTS 2 would have required less testing than a COTS 3 mission, so there would have been less delays. Of course, I can't back that up, it is just what my intuition tells me.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 03, 2012 6:31 pm

I really, really wish SpaceX had considered doing a "rendezvous" with, for example, a Progress cargo vehicle before going directly to the ISS. This would have allowed them to work out the kinks out of any software and hardware beforehand, before risking, in some peoples minds, a $100 billion asset in the ISS.I'm aware that the docking mechanisms of the Dragon and Progress are not compatible, but it wouldn't actually have to dock with Progress to prove its capability. This is because the Dragon will not dock on its own to the ISS but only come to within close proximity to the station where it will be grappled by the robot arm to link with the station.So it would suffice to just prove it could come within the specified distance to the Progress, or other orbiting vehicle, and stay within that specified distance without colliding with it. In fact it could do this multiple times with different orbiting craft to give further confidence in its capabilities.

Bob Clark

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 03, 2012 7:48 pm

On the other hand, if it approaches the ISS at least there are some astronauts looking on who can hit the abort button if there is a problem. With a trash-filled Progress that isn't the case, and if the two spacecraft collide you have a potential space junk problem in an orbit that's probably pretty close to the ISS (given that that's where the Progress came from). Having some humans as a backup is not such a bad idea.

As for combining the missions, in my eyes, the total amount of work remains the same. The tests would still have to have happened. And now you need to move around two rockets, integrate them with two Dragons, wait for two launch windows, and so on and so forth. So I don't see how doing them separately could save costs.

_________________Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhereWhat is this spell we’re under, do you care? The might to rise above it is now within your sphereMachinae Supremacy – Sid Icarus

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Fri May 04, 2012 3:36 am

No. The payoff at this stage of the COTS contract is not worth two flights. In fact, if they weren't trying to get ongoing business, they would have been best off just canceling the contract before the C2 flight.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Fri May 04, 2012 8:23 am

RGClark wrote:

I really, really wish SpaceX had considered doing a "rendezvous" with, for example, a Progress cargo vehicle before going directly to the ISS. This would have allowed them to work out the kinks out of any software and hardware beforehand, before risking, in some peoples minds, a $100 billion asset in the ISS.I'm aware that the docking mechanisms of the Dragon and Progress are not compatible, but it wouldn't actually have to dock with Progress to prove its capability. This is because the Dragon will not dock on its own to the ISS but only come to within close proximity to the station where it will be grappled by the robot arm to link with the station.So it would suffice to just prove it could come within the specified distance to the Progress, or other orbiting vehicle, and stay within that specified distance without colliding with it. In fact it could do this multiple times with different orbiting craft to give further confidence in its capabilities.

Bob Clark

But would they even need another object in orbit to test most of the systems? Could it all be 'virtual'? Just manoeuvre around an imaginary object. Of course, that doesn't tests laser rangefinders (or whatever they use), but that could be simulated.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Tue May 08, 2012 6:23 pm

Yes, it was definitely worth it. It speeds up the timeline until spacex is regularly sending dragon into space, and that is worth alot. Also, the risk is minimal - nothing significant will change about the first part of the mission; if the second part fails, the then spacex can just return to the two part plan. The safety risk is probably negligable (at least as such things go) or it wouldn't have been approved. After all, it isn't really docking by itself, it's just going close enough to be grabbed by the robotic arm. That's not significantly different from a fly-by, anyway.

_________________“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Anonymous

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Thu May 10, 2012 10:57 am

Troubadour wrote:

It's a good idea if they succeed.

But if they fail, which even SpaceX say is a definite possibility, then people will say they should have gone for two flights. But of course, there is no evidence to suggest that two flights would be any more successful.

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Mon May 14, 2012 11:19 am

And anyway, if they fail, they can still launch a second flight for a retry.

_________________Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhereWhat is this spell we’re under, do you care? The might to rise above it is now within your sphereMachinae Supremacy – Sid Icarus

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com

Re: Was the combination of the COTS 2 and 3 flights a bad idea? Posted on: Sat May 19, 2012 3:20 pm

According to the post launch news conference there is a possibility they'll have to replace the number 5 engine. In that case they will have to push the launch back to September for the next launch opportunity.This gives another reason for splitting this launch into two test flights as originally planned. As it is now you have two difficulties with the launch that have to be focused on, the successful launch itself and the successful docking.The numerous delays were caused by the uncertainty with the docking which could have been catastrophic if it failed. However if a prior launch could only be devoted to proximity rendezvous' with just satellites you could have the docking capabilities testing in real world scenarios, not just simulations, giving much better confidence in its validity.In that case also you could focus more on just making sure the launch proceeded successfully. And you would have avoided the numerous launch delays also giving better confidence in the company being able to make on time launches.

Bob Clark

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com